Resolution of racemic alpha hydroxy beta, beta dimethyl gamma butyrolactone



Patented Jan. 25, 1949 RESOLUTION OF RACEMIC a HYDROXY [3,5 DIMETHYL 7 BUTYROLACTGNE Frank 1). Pickel, Flemington, N. -J.-, and Jacob I. Fass and Saul Chodroff, Brooklyn, N. Y., as-

signors to Nopco Chemical Company, Harrison,

N. J., a corporation of New Jersey N Drawing. Application July 4, 1945,

Serial No. 603,282

7 Claims. I

The present invention relates to the resolution of racemic a hydroxy {3, 8 dimethyl 'y butyrolactone. More particularly the present invention relates to the resolution of racemic a hydroxy EL/3 dimethyl v butyrolaotone by forming d-ephed rine derivatives of the dand 1-11 hydroxy 8,5 dimethyl 7 butyrolactone and separating the so formed derivatives.

In U. S. Patent 2,319,545 there is dis-closed a process for the resolution of a hydroxy 5,5 dimethyl 7 butyrolactone by treating the lactone with an alkali such as barium or sodium hydroxide to open the ring and form the sodium salt of w dihydroxy 5,5 dimethyl butyric acid and reacting the aforesaid salt With a mineral acid salt of an alkaloid such as quinine sulfate or chloride. Although the aforementioned patent discloses the use of certain other alkaloids such as quinidine, cinchonidine, cinchonine, strychnine and brucine, these other alkaloids have not been considered particularly suitable for the resolution of the lactone and in general only the quinine salts have been used. As is well known, the llactone is used, for example, in the synthesis of -pantothenic acid.

It has now been discovered in accordance with the present invention that d-ephedrine can be used to resolve a hydroxy ,8,,8 dimethyl Y butyrolactone. Furthermore, d-ephedrine can be reacted directly with the lactone with the resultant opening of the ring to produce the corresponding d-ephedrine d-a'Y dihydroxy mi dimethyl butyric acid and d-ephedrine l-a'y dihydroxy 8,5 dimethyl butyric acid compounds. The d-ephedrine-l-ay dihydrox'y [3,6 dimethyl butyric acid compound and the d-ephedrine d-al dihydroxy ,B,,8 dimethyl butyric acid compound can be separated from one another by crystallization from suitable solvents or, in the alternative, the ephedrine derivatives can be partially separated from one another and thereafter lactonized and the lactones separated by crystallization from suitable solvents.

It is one of the objects of the present invention, therefore, to provide an economical method for the resolution of a hydroxy 6,5 dimethyl 7 butyrolactone.

A second object of the present invention is to produce novel derivatives of d-ephedrine and a7 dihydroxy [3, 8 dimethyl butyric acid.

A third object of the present invention is to 2 prepare substantially pure 1- and d-a hydroxy 13,,8 dimethyl v butyrolactones by reacting a racemic lactone with d-ephedrine in aqueous solution and thereafter separating the d-ephedrine derivatives by crystallization and/or extraction by means of suitable organic solvents.

Other objects and advantages of the present invention will become apparent from the specification and claims.

In practicing the process of the present inven tion, racemic lactone is reacted directly in aque ous solution with d-ephedrine to form a mixture of d-ephedrine l-cw dihydroxy [3,5 dimethyl butyric acid and d-ephedrine (fl-1x7 dihydroxy 5,5 dimethyl butyric acid. The water is then removed from the mixture under vacuum at a temperature below approximately C. Thereafter the reaction mixture is dissolved in a suitable solvent such as ethylene dichloride or methyl isobutyl ketone, seeded with d-ephedrine d-wy dihydroxy 6, 8 dimethyl butyric acid and cooled for a substantial period of time as, for example, three days. Other suitable solvents may also be used as, for example, methylene chloride, trichlorethylene, isopropyl acetate, mixed amyl alcohols, carbon tetrachloride, benzene, etc. preferred solvents are methyl isobutyl ketone and ethylene dichloride. A precipitate is formed which consists largely of d-ephedrine d-m' dihydroxy [3,[3 dimethyl butyric acid having a melting point, when purified, of -112 C. The mother liquor and subsequent washings contain the dephedrine l-a'y dihydroxy 5,5 dimethyl butyric acid derivative. This can be purified by concentrating to remove solvent and recrystallizing from a suitable solvent such as ethylene dichloride. Thereafter if desired, the d-ephedrine l-a'y dihydroxy 5, 8 dimethyl butyric acid may be laotonized to give the d-lactone.

The precipitated d-ephedrine Cl-a'y dihydroxy 5, 8 dimethyl butyric acid salt after filtration is slurried with a small portion of cold solvent to remove l mother liquor and again filtered. The dried salt isthen treated with caustic or acid solution to reconstitute the l-lactone. In the event causticsoda is usedthe sodium salt of the butyric I acid derived "from the l-lactone is produced liberating the ti-ephedrine. In the event acid is used, the lactone is produced directly.

Where the sodium salt of the butyric acid de- However, the

rived from the lactone produced, the ephedrine is extracted from the aqueous lactone solution with methyl isobutyl ketone or substantially any organic solvent immiscible with water, since ephedrine is soluble in substantially all organic solvents, the aqueous solution acidified to pH 1 and warmed on a steam bath for /2 hour to lactonize the hydroxy acid. The lactone is then extracted with successive amounts of a suitable solvent such as methylene chloride. Any other solvent for the lactone may also be used in this step such as ether, benzene or carbon tetrachloride. If it is desired to further purify the l-lactone it can be dissolved and recrystallized froma suitable solvent such as benzene and-petroleum ether mixtures, methyl isobutyl ketone and petroleum ether mixtures, methyl isobutyl ketone n alone, n-amyl alcohol, n-butyl alcohol and qfu'sel." Of these, however, the prefcrred solventsy are benzene and petroleum ether mixturess oil.

methyl isobutyl ketone and petroleum ether mixtures, methyl isobutyl ketone. By farthe -best solvent is methyl isobutyl ketone. In this way asubstantially pure l-iactone can be obtained:hav,-

ing a rotation of -49.8.l Instead of the direct reaction of d-ephedrine and racemic lactone, the salt of ephedrine utilizing a partial separation as previously out-, lined followed by separation of "the l-lactonefromth-e mixture of l-lactone and d-l-lactone. v

The following example serves to illustrate the present invention but is notintended to limit the same.

Example 27:88 gs. oi d-ephedrine ([aJ oiephedrinehyw drochloride 35) and 21.98 of racemie a vhydroxy 5,5 dimethyl 'y butyrolactone were dissolved in 65 ml; of, water. The mixture was heated on a steam bath for 1minutes,,,cooled and then washed with'methyiene chloride to .,re: move any unreacted ephedrine. found to be 8.

in '70 mi. of ethylene dichloride and seeded with the d-ephedrine l-lactone (d-ephedrlne-d-a'y di hydroxy 55, dimethyl butyric acid) and placed in the refrigerator. In three day aheavy precipb,

This was filtered ofif'an-d tate had formed. washed or slurried with cold ethylene dichloride to remove mother liquor.

This melting point demonstrated thatthe pre-.

cipitate was largely d-ephedrined-a'y dihydroxy,

5,5 dimethyl butyric acid (d-ephedrine l-lactone). The filtrate and washing consisted largely of d-ephedrine l-a'y dihydroxy 5,5 di-, methyl butyric acid (d-ephedrin'e d-la'ctone).

The-precipitate was dissolved in- 100 cc.,of water may be used as, for, example, ephedrine sulfate and the alkali or alkaline earth The precipitate weighed 16.9 gs. which is equivalent to 67.9% of one isomer and had a melting pointof 106 C,

The pH, was The reactant, mixture was, then concentrated under vacuumto' remove sub-. stantially all water. The residue was taken up and 15 cc. of concentrated HCl'Were added and the mixture heated for ZO-minutes on asteam both; After cooling, the lactonewas extracted with 50, 40, 30 and 30 ml. quantities of methylene.

chloride. The extracts were dried, filtered and run down. The yield of lactone was 5.53 grams or 79% of theory from the ephedrine lactone salt. Rotation of this lactone was 35.9 which was equivalent to 71% pure l-lactone. It was then recrystallized from 5 cc. of benzene and 2 /2 cc. of petroleum ether. A yield of 3 /2 grams and a rotation of --43.8, equivalent to 86.5% l-lactone, was obtained. The mother liquor, i. e. acid solution, consisted largely of d-Qphedrine. The ephedrine was recoveredsfrom the acid .-solution by making the solution alkaline and extracting with a suitable organic solvent.

Having described our invention, what we claim: asnew and desire to secure by Letters Patent is:.

1. In a process for the resolution of racemic a hydroxy 5,5 dimethyl Y butyrolactone, the step whichdcomprises reacting the lactone with dephedri'ne-to form a d-ephedrine derivative of 1-01 dihydroxy 5,5 dimethyi butyric acid and a dsephedrine derivative of d-w dihydroxy 5,5 dimethylbutyric acid at a temperature below the decomposition temperatures of said ephedrine derivatives.

2., A process for the resolution of racemicl-u hydroxy 5,5 dimethyl V butyrolaotone comprisingreacting the said lactone with d-ephedrine to form a d-ephedrine derivative of 1-00 dihydroxy- 5,5 .dimethyl butyric acid and a d-ephedrine sition temperatures of said ephedrinederiva-s tives, dissolving the reactionproducts ina Sole" vent. for said ephedrine derivatives and.crystallizing the d-ephedrine derivative of d-zx'Y- dihye droxy 5,5 .dimethyl butyric acid therefrom.-

3. As a new compound a salt selected from the group consisting of a d-ephedrine salt of .l-ay dis hydroxy 5,5 dimethyl butyric acid and a dephedrine saltot d-m dihydroxy 5,5 dimethyl-butyric acid.

4. As a new compound the d-ephedrine salt, of

d-ay dihydroxy 5,5 ,dimethyl butyric acid;

5.As a new compound the d-ephedrine salt otl-ovy dihydroxy 5,5 dimethylbutyricacid.

6. A proc,ess for the resolution of racemic a hy,,- droxy 5,5 dimethyl 'y butyrolactone which com-p prises ,reactingthe aforesaid lactone with -d-.,

ephedrine to form a d-ephedrine derivative of l-a-y. dihydroxy, 5,5 dimethyl butyric .acid and; a d-ephedrine derivative of d-wy dihydroxy 5,5 di-.v

methylbutyric acid at a temperature .below'the.

decomposition temperatures of said ephedrine. derivatives, dissolving the reaction products insa solvent ,ior, said ephedrine derivatives, crystallize;

ingthe d-ephedrine derivative of d-a'y. dihydrioxy, 5,5 dimethylbutyric acid from the solution, lacs;-

tonizing the,d-ephedrine d-u'y dihydroxy 5,5 di.--; methyl butyric acid to produce l-a hydroxy, 5,5

dirnethyl 'y butyrolactone, dissolving the l-lac tone, infla solvent for the l-lactone, and cooling,

the solution to precipitate purified 1-11 hydroxy,

5,5 dimethyl 'y butyrolactone therefrom.

7.'A process for theresolution of racemic a hydroxy 5,5 dlmethyl 'y butyroiactone which comprises reacting the aforesaid lactone -.with d-ephedrine toform a d-ephedrine derivative. of l-ay ,dihydroxy 5,5 .dimethylbutyric acidand a, d-ephedrine derivative of d-wy dihydroxy. 5,5 dimethyl butyric acid at a temperature belowthe decomposition. temperatures of said ephedrine;

derivatives, dissolvingthe mixtures oithe bu tyric acid compoun-dsina solvent, crystallizing med-ephedrine derivative of .d-wy dihydroxy, 5,5

dimethyl butyric acid from the solution, lactonizing the d-ephedrine (E-wy dihydroxy fifi dim-ethyl butyric acid to produce L-a hydroxy 5, 3 dimethyl v butyroiactcne, dissolving the lactone in methyl iscbut-yl ketone, and cooling the solution is pre cipitate purified 1-oc hydroxy [3,5 dimethyl 'y bu tyrolactone therefrom.

FRANK D. PICKEL.

JACOB I. FASS.

SAUL CI-IODROFF.

REFERENCES cum UNITED STATES PATENTS Name Date Harris et a1 May 18, 1943 2,328,00Q Finkelstein Aug. 31, 1943 10 OTHER REFERENCES Organic Chemistry-An Advanced Treatise, by Gilman, vol. I, 2nd edition (1943), pp. 254-259.

Certificate of Correction Patent No. 2,460,239. January 25, 1949.

FRANK D. PICKEL ET AL.

11 of the above It is hereby certified that error appears in the printed specificatio numbered patent requiring correction as follows:

Column 4, lines 73 and 7 4, claim-7 strike out mixtures of the butyric acid comounds in a solvent and insert instead reaction products in a solvent for said ephedrine derivatives; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Ofllce.

Signed and sealed this 7th day of June, A. D. 1949.

THOMAS F. MURPHY,

Am'lta'nt flommissioner of Patents.

Certificate of Correction Patent No. 2,460,239. January 25, 1949. FRANK D. PIGKEL ET AL. It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 4, lines 73 and 7 4, claim 7, strike out mixtures of the butyric acid comounds in a solvent and insert instead reaction products in a solvent for seed ephedrine derivatives; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 7th day of June, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommiasz'mler of Patents. 

